PHOTOSYNTHESISPHOTOSYNTHESIS

What do you know? What do you know?

What do you want to What do you want to know? know?

Photosynthesis uses sun energy to make sugar (glucose) (

– Plants and algae only – Autotrophs- make their own food – Heterotrophs- can’t make their own food

All living organisms ( including plants) use cellular respiration to get energy from their food

Photosynthesis Photosynthesis EQUATIONEQUATION

Reactants- light , carbon Reactants- light , carbon dioxide, & waterdioxide, & water

Products: sugar and oxygenProducts: sugar and oxygen

Sunlight+6CO2+ 6H20 C6H12O6 + __O2

Light & Pigments

•Sunlight is “white” but contains mixtures of visible wavelengths

•Chlorophyll is a PIGMENT in the chloroplast of the plant cell that absorbs light

- Leaves absorb blue-violet & red-orange light very well - Green light is reflected- why plants look green!

Chlorophyll a - Absorbs all colors of light

except green - Plays major role in light

reactions of photosynthesis

Chlorophyll b - Appears yellow-green- Absorbs additional light

Xanthophyll -Yellow pigment

Carotene -Red & orange pigments

MajorPigments

MinorPigments

Types of Pigments

LOCATION OF PHOTOSYNTHESISChloroplasts organelle in plant cells

** Chloroplast has double membrane **** Chloroplast has double membrane **

ThylakoidsThylakoids: sac-like photosynthetic : sac-like photosynthetic

membranesmembranes– Arranged in stacks called GRANAArranged in stacks called GRANA– Have Have chlorophyllchlorophyll and other pigments and other pigments

StromaStroma: Fluid area surrounding : Fluid area surrounding

thylakoidsthylakoids

CHLOROPLAST STRUCTURE

Boozeman 5:00 Minutes

* Light-Dependent* Light-Dependent: :

takes place in takes place in

thylakoids- thylakoids-

* Calvin Cycle:* Calvin Cycle:

takes place in takes place in

stromastroma

Light ReactionLight Reaction

1.1. Chlorophyll molecules in Chlorophyll molecules in thylakoid capture light thylakoid capture light energyenergy

2.2. This energy releases This energy releases electrons from Helectrons from H22OO

3.3. HH22O then splits into OO then splits into O22 and and H+ H+

4.4. Oxygen is a "waste product" Oxygen is a "waste product" & escapes to the & escapes to the atmosphereatmosphere

So what happens to the electrons and So what happens to the electrons and hydrogen ions?hydrogen ions?

• Chloroplasts use them to make an Chloroplasts use them to make an energy-rich molecule called energy-rich molecule called NADNADPPH H and and ATPATP

• The overall result of the light reaction?The overall result of the light reaction?

Light + HLight + H220 Oxygen + NADPH + 0 Oxygen + NADPH + ATPATP

Light ReactionLight Reaction

Light reaction Light reaction is charging up the is charging up the ““batterybattery”” needed to synthesize sugars needed to synthesize sugars in Calvin Cyclein Calvin Cycle

- ADP and NADP+ recycle - ADP and NADP+ recycle

Calvin CycleCalvin Cycle

• Does NOT use light at Does NOT use light at allall

• Can use energy that Can use energy that was made in light was made in light cycle to form sugarcycle to form sugar

1.1. Occurs in the STROMA.Occurs in the STROMA.

2.2. Uses COUses CO22 and energy powered by ATP and energy powered by ATP and NADPH to produce sugarand NADPH to produce sugar

3.3. NAPDH and ATP are recycled back to the NAPDH and ATP are recycled back to the Light Cycle for Light Cycle for ““rechargingrecharging””

The Calvin Cycle

Reactants:Reactants:

Products:Products:

Two ProcessesTwo Processes

Light ReactionLight Reaction Calvin CycleCalvin Cycle

Online Activity 8.1- Animation of Light and Dark Cycles

Page 6 –Start

Factors Affecting Factors Affecting PhotosynthesisPhotosynthesis

• TemperatureTemperature• Light intensityLight intensity

Carbon Cycle